1. Field of the Invention
This present invention relates to fluid mixtures, more particularly to, an apparatus for mixing natural gas and air to obtain various predetermined gas-air concentrations.
2. Description of Related Art
The odor intensity of gas-air mixtures is useful in determining compliance with the gas safety code requirements in many states. These codes typically require that the natural gas should be odorized such that it can be smelled by a person at a predetermined concentration of, for example, one-fifth the lower flammability limit of the gas (i.e., one percent of gas in air).
An example of an apparatus used for producing a gas-air mixture is found in U.S. Pat. No. 4,106,910, issued Aug. 15, 1978, to Saunders. This patented apparatus uses a venturi and pressurized air for mixing gas with air by dilution.
One problem with the above patented apparatus is that it does not operate adequately in low pressure applications. Another problem is that the apparatus requires pressurized air for mixing the gas and air to obtain the gas-air concentration. It is, therefore, believed that a need exists to produce various gas-air concentrations at low pressures without the use of pressurized air.
It is one object of the present invention to provide an apparatus for mixing gas and air at various predetermined concentrations. It is another object of the present invention to provide an apparatus that mixes gas and air at low pressures. It is still another object of the present invention to mix gas and air without the use of pressurized air.